Chiral N-heterocyclic carbene-catalyzed generation of ester enolate equivalents from α,β-unsaturated aldehydes for enantioselective Diels–Alder reactions
作者:Juthanat Kaeobamrung、Marisa C. Kozlowski、Jeffrey W. Bode
DOI:10.1073/pnas.1007469107
日期:2010.11.30
The catalytic generation of chiral ester enolate equivalents from alpha,beta-unsaturated aldehydes with chiral N-hetereocyclic carbene catalysts makes possible highly enantioselective hetero-Diels-Alder reactions. The reactions proceed under simple, mild conditions with both aliphatic and aromatic substituted enals as substrates. Previous attempts to employ these starting materials as enolate precursors
使用手性 N-杂环卡宾催化剂从 α,β-不饱和醛催化生成手性酯烯醇化物等价物使得高度对映选择性的杂狄尔斯-阿尔德反应成为可能。反应在简单、温和的条件下进行,脂肪族和芳香族取代的烯醛作为底物。先前尝试将这些起始材料用作烯醇化物前体,通过催化产生的均烯醇化物等价物得到结构不同的产物。烯醇生成成功的关键是用于生成活性 N-杂环卡宾催化剂的催化碱的强度。为了补充这些研究,我们使用计算方法研究了烯醇结构,发现它更喜欢垂直于三唑核的构象。